Re:Police Say Uber Is Likely Not at Fault for Self-Driving C...
by Balgair on Tuesday March 20, 2018 @12:50PM
(#16630282)
For the people that practice street-math, Kinetic Energy goes as (velocity)^2. So halving the speed reduces the energy to 1/4. A third of the speed is 1/9th the energy. etc.
As you go faster, your energy goes up exponentially. This is why there are bitter fights about increasing the speed limit on roads; they become exponentially less safe (big caveats apply, naturally).
Re:Police Say Uber Is Likely Not at Fault for Self-Driving C...
by rripken on Tuesday March 20, 2018 @01:06PM
(#16630448)
So if you are going 10% faster (38 vs 35) you have 121% the kinetic energy.
Re:Police Say Uber Is Likely Not at Fault for Self-Driving C...
by Balgair on Tuesday March 20, 2018 @02:19PM
(#16631115)
My math says it's ~1.18 times more KE.
But yes, about 1/5th more KE with just a 3 mph difference.
Re:Police Say Uber Is Likely Not at Fault for Self-Driving C...
by sol_remmy on Tuesday March 20, 2018 @11:54AM
(#16629677)
Except if the speed limit is 35, you need to drive 35. You can't drive 25 just to be more "defensive", that will get you a ticket.
Re:Police Say Uber Is Likely Not at Fault for Self-Driving C...
by Balgair on Tuesday March 20, 2018 @12:46PM
(#16630250)
Typically, no. There are some municipalities and areas of road where there is a minimum speed limit, but in the US, those are very rare. Granted, a law enforcement officer has wide jurisdiction to determine if you are 'safe' to drive and a low speed may become unsafe. But they are unlikely to ticket you and are more likely to try to help you out. Driving under the speed limit may be annoying, but it is nearly-universally not illegal.
Re:Police Say Uber Is Likely Not at Fault for Self-Driving C...
by 1812Overture on Tuesday March 20, 2018 @08:41PM
(#16634230)
It's actually more dangerous as it forces other cars to change lanes to get around you.
Re:Police Say Uber Is Likely Not at Fault for Self-Driving C...
by galdosdi on Wednesday March 21, 2018 @12:10AM
(#16635394)
WTF? Spoken like an inveterate speeder... it's at best equally dangerous, the effect you are speaking of happens for both higher and lower speeds. At low speeds, other cars pass you. At high speeds, you pass other cars. Either way, every pass is an opportunity for failure, and the probability is higher the higher the relative speed. However, the road, barriers, trees, etc, is always going at 0 mph, so not just the relative, but also absolute speed control crash severity. Twice the speed means 4 times the kinetic energy... speed kills.
Re:Police Say Uber Is Likely Not at Fault for Self-Driving C...
by 1812Overture on Thursday March 22, 2018 @04:45PM
(#16652550)
Re:Police Say Uber Is Likely Not at Fault for Self-Driving C...
by galdosdi on Friday March 23, 2018 @05:29AM
(#16656348)
What's your point exactly? The Quora poster's argument is just a rehash of the OP and also can be restated symmetricly for over speeding as for underspeeding and thus adds nothing here.
It also fails to address my point about kinetic energy, which is proportional to the square of speed!
Re:Police Say Uber Is Likely Not at Fault for Self-Driving C...
by DoTheNeedful on Tuesday March 20, 2018 @03:43PM
(#16631863)
> Typically, no.
Typically it will get you pulled over. Obstructing the flow of traffic is a thing.
A very rough calculation: v(t) = -μgt + v_0. To reach 32 kph or 20 mph, t ~= 0.82/μ, guessing a fair μ=0.8 and the chart here https://ec.europa.eu/transport/road_safety/specialist/knowle...